docs: def upload(self, filename, input, packethook=None, timeout=SOCK_TIMEOUT):
          """This method initiates a tftp upload to the configured remote host,
          uploading the filename passed. It reads the file from input, which
          can be a file-like object or a path to a local file. If a packethook
          is provided, it must be a function that takes a single parameter,
          which will be a copy of each DAT packet sent in the form of a
          TftpPacketDAT object. The timeout parameter may be used to override
          the default SOCK_TIMEOUT setting, which is the amount of time that
          the client will wait for a DAT packet to be ACKd by the server.
  
          Note: If input is a hyphen, stdin is used."""
          self.context = TftpContextClientUpload(self.host,
                                                 self.iport,
                                                 filename,
                                                 input,
                                                 self.options,
                                                 packethook,
                                                 timeout,
                                                 localip = self.localip)
          self.context.start()
          # Upload happens here
          self.context.end()
  
          metrics = self.context.metrics
  
          log.info('')
          log.info("Upload complete.")
          if metrics.duration == 0:
              log.info("Duration too short, rate undetermined")
          else:
              log.info("Uploaded %d bytes in %.2f seconds" % (metrics.bytes, metrics.duration))
              log.info("Average rate: %.2f kbps" % metrics.kbps)
          log.info("%.2f bytes in resent data" % metrics.resent_bytes)
          log.info("Resent %d packets" % metrics.dupcount)